Stain resistance, water repellency and resistance to microbial growth are important in many uses of textile materials. In restaurants, for example, table cloths and seating upholstery often lack stain resistance and are subject to rapid water penetration. These properties necessitate frequent cleaning and/or replacement of such items. Although one generally views microbial growth as associated with fibers of biologic origin such as cotton, wool, linen and silk, in the field of marine use, the high relative humidity renders even synthetic polymer textiles, such as polyesters and polyamides, subject to microbial growth, which is also true of many other outdoor uses.
The term "water repellant" as used herein means essentially impermeable to water, i.e. treated textile can support a considerable column of water without water penetration through the fabric. Such behavior is sometimes termed "water resistant." However, the last term generally implies a lesser degree of water repellency and further can be confused with the chemical use of "water resistant" to refer to coatings which are chemically stable to water or which will not be washed off by water. Hydrophobicizing topical treatments are incapable of providing the necessary degree of water repellency as that term is used herein.
Textile fabrics may be made water repellant by various processes. For example, textile fabrics may first be scoured with a soap solution and then treated with a composition which may include zinc and calcium stearates as well as sodium soaps. The long chain carboxylic acid hydrophobic compounds provide a limited amount of water repellency. It is also possible to render fabrics liquid resistant by treating the fabric with commercially available silicone, for example poly(dimethylsiloxane).
To overcome problems associated with water absorption and stain resistance, resort has been made to synthetic leathers and polyvinylchloride (vinyl) coated fabrics. However, these fabrics do not have the hand or feel of cloth. Moreover, although attempts have been made to render such materials water vapor permeable, these attempts have met with only very limited success, as evidenced by the failure of synthetic leather to displace real leather in high quality seating and footwear.
Applications of relatively small amounts of fluorochemicals such as the well known SCOTCHGUARD.TM. and similar compounds also may confer a limited degree of both water repellency and stain resistance. However, for optimal water repellency, it has proven necessary to coat fabrics with thick polymeric coatings which completely destroy the hand and feel of the fabric. Examples include vinyl boat covers, where the fabric backing is rendered water resistant by application of considerable quantities of polyvinylchloride latex or the thermoforming of a polyvinyl film onto the fabric. The fabric no longer has the hand and feel of untreated fabric, but is plastic-like. Application of polyurethane films in the melt has also been practiced, with similar results. However, unless aliphatic isocyanate-based polyurethanes are utilized, the coated fabric will rapidly weather.
It would be desirable to provide a fabric that allows water vapor to pass through the fabric while prohibiting the passage of liquid. It would also be desirable to provide a method of producing a liquid repellant, stain resistant, antimicrobial fabric. It would further be desirable to provide a liquid repellant, stain resistant, antimicrobial fabric that retains its natural hand and texture, is easy to handle, and economical to produce.